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Kidney Week

Abstract: SA-PO323

Real-Time ATP Imaging Reveals the Metabolic State During Kidney Development

Session Information

Category: Development, Stem Cells, and Regenerative Medicine

  • 600 Development, Stem Cells, and Regenerative Medicine

Authors

  • Mii, Akiko, Kyoto University Graduate School of Medicine, Kyoto, Japan
  • Yamamoto, Shinya, Kyoto University Graduate School of Medicine, Kyoto, Japan
  • Yamamoto, Shigenori, Kyoto University Graduate School of Medicine, Kyoto, Japan
  • Yanagita, Motoko, Kyoto University Graduate School of Medicine, Kyoto, Japan
Background

Maternal malnutrition is associated with a reduced nephron number and an increased risk of hypertension and chronic kidney disease in later life. However, very little is known about what determines the nephron number, and about the metabolic state during nephrogenesis.

Methods

We focused on the cytosolic adenosine 5-triphosphate (ATP) level and its changes to examine an energy metabolism in embryonic kidneys. To explore the spatiotemporal dynamics of the cytosolic ATP level, we used transgenic mice expressing the cytosolic ATP-FRET biosensor, called GO-ATeam2 mice. We performed visualization and analysis of cytosolic ATP level in real-time ex-vivo imaging during branching nephrogenesis and examined the dependence of ATP production on glycolysis and oxidative phosphorylation during nephrogenesis.

Results

We succeeded in visualizing the cytosolic ATP level at a single cell level and investigated the spatiotemporal dynamics of the cytosolic ATP level in both ureteric bud (UB) and cap mesenchyme (CM) cells. The UB forms the collecting ducts through repeated bifurcation of the ureteric tree, while the CM differentiates into nephron epithelial cells. The reciprocal interaction between UB and CM cells is crucial for proper kidney development. During branching nephrogenesis, ATP levels of UB tip cells were significantly lower than those of UB stalk and CM cells. Glycolytic inhibition in the early phase of metanephric kidney (embryonic day E12.5) severely reduced the ATP level in both cells in a dose dependent manner, but ATP reduction was faster and more prominent in UB cells rather than in CM cells. In addition, the expression of specific markers for UB and CM cells were significantly reduced and electron microscopy images showed a loosening of cell-cell adhesion and irregular cell alignment in CM cells after glycolytic inhibition. Furthermore, glycolytic inhibition resulted in suppressed UB branching and reduced number of both branch segments and UB tips. On the other hand, these effects were not observed by an oxidative phosphorylation inhibitor.

Conclusion

The mice allowed us to perform real-time ex-vivo ATP imaging of embryonic kidneys. We found that UB branching was heavily dependent on glycolysis and that UB cells in the early branching phase were sensitive to glycolytic inhibition.